I agree that the serial number format is consistent with Giant of Taiwan and, if so, indicates late January 1988. While the bicycle has been substantially rebuilt, the brake calipers, which appear to be Shimano Exage Motion, would be consistent with the timeframe, as would be the fade paint scheme. I'm not concerned with the serial number location, as manufacturers often employed different locations for different geographic regions and I notice that the OP is located in Australia.
As for the branding, Pesaro is an Italian city on the upper Adriatic coast. Naturally, there is a bicycle shop named Pesaro Bici but according to the website, it's only been in existance since 2012. I'm guessing it's a house brand for some company who's founder has the surname Pesaro or who's heritage stems from the Pesaro region of Italy.